bump containerd/fifo a9fb20d87448d386e6d50b1f2e1fa70dcf0de43c

- containerd/fifo#17 Expose underlying file's `SyscallConn` method

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

vendor.conf

@@ -120,7 +120,7 @@ google.golang.org/genproto                          694d95ba50e67b2e363f3483057d
 
 # containerd
 github.com/containerd/containerd                    ceba56893a76f22cf0126c46d835c80fb3833408
-github.com/containerd/fifo                          3d5202aec260678c48179c56f40e6f38a095738c
+github.com/containerd/fifo                          a9fb20d87448d386e6d50b1f2e1fa70dcf0de43c
 github.com/containerd/continuity                    004b46473808b3e7a4a3049c20e4376c91eb966d
 github.com/containerd/cgroups                       4994991857f9b0ae8dc439551e8bebdbb4bf66c1
 github.com/containerd/console                       c12b1e7919c14469339a5d38f2f8ed9b64a9de23

vendor/github.com/containerd/fifo/raw.go

@@ -0,0 +1,116 @@
+// +build go1.12
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package fifo
+
+import (
+	"syscall"
+
+	"github.com/pkg/errors"
+)
+
+// SyscallConn provides raw access to the fifo's underlying filedescrptor.
+// See syscall.Conn for guarentees provided by this interface.
+func (f *fifo) SyscallConn() (syscall.RawConn, error) {
+	// deterministic check for closed
+	select {
+	case <-f.closed:
+		return nil, errors.New("fifo closed")
+	default:
+	}
+
+	select {
+	case <-f.closed:
+		return nil, errors.New("fifo closed")
+	case <-f.opened:
+		return f.file.SyscallConn()
+	default:
+	}
+
+	// Not opened and not closed, this means open is non-blocking AND it's not open yet
+	// Use rawConn to deal with non-blocking open.
+	rc := &rawConn{f: f, ready: make(chan struct{})}
+	go func() {
+		select {
+		case <-f.closed:
+			return
+		case <-f.opened:
+			rc.raw, rc.err = f.file.SyscallConn()
+			close(rc.ready)
+		}
+	}()
+
+	return rc, nil
+}
+
+type rawConn struct {
+	f     *fifo
+	ready chan struct{}
+	raw   syscall.RawConn
+	err   error
+}
+
+func (r *rawConn) Control(f func(fd uintptr)) error {
+	select {
+	case <-r.f.closed:
+		return errors.New("control of closed fifo")
+	case <-r.ready:
+	}
+
+	if r.err != nil {
+		return r.err
+	}
+
+	return r.raw.Control(f)
+}
+
+func (r *rawConn) Read(f func(fd uintptr) (done bool)) error {
+	if r.f.flag&syscall.O_WRONLY > 0 {
+		return errors.New("reading from write-only fifo")
+	}
+
+	select {
+	case <-r.f.closed:
+		return errors.New("reading of a closed fifo")
+	case <-r.ready:
+	}
+
+	if r.err != nil {
+		return r.err
+	}
+
+	return r.raw.Read(f)
+}
+
+func (r *rawConn) Write(f func(fd uintptr) (done bool)) error {
+	if r.f.flag&(syscall.O_WRONLY|syscall.O_RDWR) == 0 {
+		return errors.New("writing to read-only fifo")
+	}
+
+	select {
+	case <-r.f.closed:
+		return errors.New("writing to a closed fifo")
+	case <-r.ready:
+	}
+
+	if r.err != nil {
+		return r.err
+	}
+
+	return r.raw.Write(f)
+}

vendor/github.com/containerd/fifo/readme.md

@@ -1,6 +1,7 @@
 ### fifo
 
 [![Build Status](https://travis-ci.org/containerd/fifo.svg?branch=master)](https://travis-ci.org/containerd/fifo)
+[![codecov](https://codecov.io/gh/containerd/fifo/branch/master/graph/badge.svg)](https://codecov.io/gh/containerd/fifo)
 
 Go package for handling fifos in a sane way.
 
@@ -30,3 +31,14 @@ func (f *fifo) Write(b []byte) (int, error)
 // before open(2) has returned and fifo was never opened.
 func (f *fifo) Close() error 
 ```
+
+## Project details
+
+The fifo is a containerd sub-project, licensed under the [Apache 2.0 license](./LICENSE).
+As a containerd sub-project, you will find the:
+
+ * [Project governance](https://github.com/containerd/project/blob/master/GOVERNANCE.md),
+ * [Maintainers](https://github.com/containerd/project/blob/master/MAINTAINERS),
+ * and [Contributing guidelines](https://github.com/containerd/project/blob/master/CONTRIBUTING.md)
+
+information in our [`containerd/project`](https://github.com/containerd/project) repository.